Human hair becomes soiled due to its contact with the surrounding atmosphere and, to a greater extent, from sebum secreted by the head. The build-up of the sebum causes the hair to have a dirty feel and an unattractive appearance. The soiling of the hair necessitates it being shampooed with frequent regularity.
Shampooing relates to the cleaning of hair by removing excess soil and sebum. However, the shampooing process has disadvantages in that the hair is left in a wet, tangled and generally unmanageable state. A variety of approaches have been developed to alleviate the after-shampoo problems. These approaches range from the inclusion of hair conditioning aids in shampoos to post-shampoo application of hair conditioners, i.e., hair rinses. Hair rinses typically work by depositing a polymeric film or other material onto the hair. However, such solutions to a very prevalent problem have not been fully satisfactory for the following reasons. Hair rinses are generally liquid in nature and must be applied in a separate step following the shampooing step, left on the hair for a length of time, and rinsed with fresh water. This, of course, is time consuming and is not convenient.
While shampoos have been disclosed which contain conditioning aids, they have not been totally satisfactory for a variety of reasons. One problem relates to compatibility problems between good cleaning anionic surfactants and the fatty cationic agents which are good conditioning agents. This has caused other surfactants such as nonionics, amphoterics and zwitterionics to be experimented with by the shampoo industry.
The use of these other surfactants solved many of the compatibility problems but still did not provide complete answers in all areas. For instance cationic conditioners may not deliver the required level of softness desired by users. Materials which have been found to increase softness are silicones, both those which are soluble as well as insoluble in the shampoo matrix.
Even with the inclusion of silicones, one unsolved problem is that of providing satisfactory static control as well as other hair conditioning properties such as softness and wet and dry combability. Moreover, the use of silicones in shampoo formulations has certain inherent disadvantages such as: (1) silicones act as defoamers, thus reducing the amount of foam (lather) formed during the hair washing process; (2) silicones are prone to leave an undesirable residue on the hair, even after rinsing, which cause the hair to be unnecessarily weighed down; (3) the undesirable residue imparted onto the hair by the silicones, has a tendency to quickly attract dirt particles present in the environment, thus making the hair unseemingly dirty/greasy looking; and (4) silicones are typically difficult to incorporate into formulations due to their inherent chemical incompatability with many of the components contained therein.